Erodium trifolium

Today’s photographs and write-up are courtesy of Ian Gillam, one of UBC Botanical Garden’s many exceptional Friends of the Garden. Thank you! Ian writes:

Erodium trifolium is a member of the Geraniaceae native to North Africa. Like many plants of the region it grows in winter, flowers in early spring and is largely dormant in summer drought.

In Vancouver, Erodium trifolium is reasonably hardy outdoors in a well-drained and sheltered area, such as close to the south side of a house. In exceptionally cold winters plants may be damaged or killed.

In common with the related genera Geranium and Pelargonium, successfully pollinated flowers of Erodium produce a lengthening style from the centre of their flowers, growing to about 2.5 cm in this species. As this rostrum develops, the flower heads take on a fanciful resemblance to the heads of long-beaked birds. Botanical names of Geranium, Pelargonium and Erodium derive from Greek names of crane, stork and heron, respectively. Their common names also refer to these birds’ long bills. As the seeds mature, the fruiting body turns brown and dries. The ovary splits into five segments, termed mericarps, each containing a single seed. Each mericarp is attached to a tail, an awn, that curls up to pull away from the rostrum.

As Erodium trifolium awns dry, the lower parts coil into tight helices of about five turns, leaving a terminal section curved but uncoiled. A single mericarp is shown above.

The pointed tip has a slight hook and many short, backward-pointing bristles. These features may help mericarps attach and penetrate into fur or feathers, possibly aiding distribution of seeds. Mericarps fall to the ground with the heavier end first. With luck the tip may lodge in some slight crack in the soil. The awn is sensitive to moisture and a slight wetting, even by dew, causes it to unwind within minutes. If the protruding tail catches on a piece of gravel or a plant’s stem the power of the unwinding is transferred to the mericarp, thrusting it forward and screwing it into the ground (with a left-hand thread). Should the attempt fail, the sun’s warmth will soon cause the awn to coil again and wind may move the whole to a better location for another try at planting.

Erodium trifolium
Erodium trifolium

7 responses to “Erodium trifolium”

  1. Harry Thomas

    The seed is amazing. I wonder what the time period was that Mother Nature, Natural Selection, took to develop it. We all consider that man made the first machines, but I think plants beat us to it.

  2. Ann Kent HTM

    Thank you, Ian, for the fascinating information about the mericarp. This is a story that will delight those I work with in residential care where working with seeds and pods and cones is a favourite part of therapeutic horticulture programs. Ann.

  3. Annie in Texas

    I agree with you, Harry. I imagine our ancestors got many of their ideas for tools by studying plants. Of course that takes some smarts to begin with, we didn’t do so bad.
    Lovely flowers.

  4. dr bob

    Place one of the mericarps in the open palm of you hand. Enough water vapor is released from you palm to cause the mericarp to wind it’s way between your fingers. It really only takes 30 seconds or a minute. Several species of Erodium are now naturalized in California, and they all do this. A slick adaptaion that screws the seed into the soil at just the right depth for germination and establishment. The same seeds can bore their way through the skin of animals in whose fur the mericarps may become lodged, causing painful infections. The Spanish galleons carried bags of these seeds to feed to their captive livesotck in the hold (they had no refigeration, just imagine what the holds smelled like!), small wonder that these were some of the first European species to be introduced to California’s flora: seeds of several Erodium species have been isolated from the adobe bricks from the very earliest Spanish missions in California.

  5. elizabeth a airhart

    please ian how did you take the first picture
    looks like a heavenly being speeding through space
    tis thanksgiveing here in the states i would like to say thank you
    to botaday for bringing beauty and interest into my life
    each day same for the comments and the voices behind them
    its still black friday here and since you do offer free shipping
    i bid thee all bon jour

  6. Ian Gillam

    elizabeth,
    Since you ask, a good quality close-up lens on the camera’s lens. Black background kept out of focus by supporting the mericarp on a clean glass sheet, angled to avoid reflections and with strongly directional lighting. Then a deal of trial and error. The tail of the awn is unavoidably out-of-focus. Improving that would require more time, patience and equipment than available.

  7. Daniel Mosquin

    A follow-up to this entry, suggested by Eric Hunt: Unraveling the Mystery of Self-Planting Seeds

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